This invention relates to stabilization of shelf life conductivity of conductive organic and inorganic coatings, and is particularly directed to a method of stabilizing shelf life conductivity of conductive substrate coatings of polypyrrole and nickel sulfide.
Conductive coatings can be made from organic conductive polymers such as polypyrrole or from inorganic conductive material such as nickel sulfide. These conductive coatings can be readily impregnated into substrate materials such as fiberglass, as disclosed in U.S. Pat. No. 4,617,228 to Newman et al, and in U.S. application Ser. No. 394,260, filed Aug. 7, 1989, issued as U.S. Pat. No. 5,002,824 to Warren, and assigned to the same assignee as the present application, and the resulting coated substrate is subsequently laminated to make conductive composite structural materials and parts.
It has been demonstrated that these conductive substrate impregnated coatings are not completely electrically stable in the neat unprotected state, a condition which is unacceptable when being held on the shelf awaiting lamination.
U.S. Pat. No. 4,692,225 to Witucki et al discloses a method of stabilizing electrically conductive polymers such as polypyrrole to hostile environments. The method comprises encapsulating the conductive polymer, e.g. polypyrrole, preferably in the form of a composite of a substrate, such as fiberglass fabric, impregnated with the conductive polymer, with an epoxy, polyimide or bismaleimide resin, as an encapsulating agent. The preferred method involves pre-pregging the fabric of the conductive composite with an epoxy resin and curing the resulting system.
It is an object of the present invention to provide a novel method of stabilizing shelf life conductivity of conductive organic polymers such as polypyrrole, or conductive inorganic materials such as nickel sulfide, on a substrate.
Another object of the invention is the provision of procedure for stabilizing shelf life conductivity of polypyrrole or nickel sulfide conductive coatings on a substrate, by incorporating certain protective materials into such coatings or by providing an overcoating of certain protective materials.
A still further object is to provide a process for stabilizing the shelf life conductivity of a substrate, such as fiberglass fabric, impregnated with conductive polypyrrole or conductive nickel sulfide.
A still further object is the provision of improved shelf life stabilized conductive substrate coatings of polypyrrole or nickel sulfide.